It is important for the particle therapy system to verify the tumor position in forming a dose distribution conforming to the shape of the tumor.
Particularly, in order to improve the accuracy of the dose distribution over the tumor region that moves in keeping with body motions such as respiration, there is provided a method for irradiation with the particle beam in synchronism with respiration through measurement of the motion of the chest.
Patent Literature 1 describes a technique whereby a CT image for treatment planning is obtained using a CT scanner preparatory to treatment, the obtained CT image being used to determine the region to be irradiated with the particle beam.